<?php
class Memory_utils {
	
	public function evaluate_ef($ef, $score)
	{
		if($ef == 0)
		{
			return 2.5;
		}
		else
		{
			$new_ef = $ef + (0.1 - (5 - $score) * (0.08 + (5 - $score) * 0.02));
			$new_ef = $new_ef < 1.3 ? 1.3 : $new_ef;
			return $new_ef;
		}
	}
}
?>